Cerebral low-density lipoprotein (LDL) uptake is stimulated by acute bile drainage

Although the cholesterol pool in the central nervous system is considered to be relatively stable, few studies have tested this assumption. The aim of the study was to gain further information on the communication between the extracerebral organs and the brain as far as cholesterol and lipoprotein transport are concerned. Receptor-dependent as well as receptor-independent LDL uptake in the brain were measured, by established methods, after constant 1-h intravenous infusions of [14C]sucrose-labelled hamster LDL and methylated human LDL, both in hamsters with an acute bile fistula and in control animals with an intact enterohepatic circulation. The receptor-dependent LDL uptake in the brain promptly showed a significant increase after the construction of the bile fistula. However, there was no difference in the receptor-independent LDL uptake between the bile fistula and control animals. The studies indicate the presence of close communications between extracerebral and brain cholesterol. Changes in the extracerebral compartments of cholesterol are, apparently, readily sensed by the LDL receptor in the brain and promptly evoke appropriate modifications in its activity.